Effect of impurities in the description of surface nanobubbles: Role of nonidealities in the surface layer\ud

In a recent study [ S. Das, J. H. Snoeijer and D. Lohse Phys. Rev. E 82 056310 (2010)], we provided quantitative demonstration of the conjecture [ W. A. Ducker Langmuir 25 8907 (2009)] that the presence of impurities at the surface layer (or the air-water interface) of surface nanobubbles can substantially lower the gas-side contact angle and the Laplace pressure of the nanobubbles. Through an analytical model for any general air-water interface without nonideality effects, we showed that a large concentration of soluble impurities at the air-water interface of the nanobubbles ensures significantly small contact angles (matching well with the experimental results) and Laplace pressure (though large enough to forbid stability). In this paper this general model is extended to incorporate the effect of nonidealities at the air-water interface in impurity-induced alteration of surface nanobubble properties. Such nonideality effects arise from finite enthalpy or entropy of mixing or finite ionic interactions of the impurity molecules at the nanobubble air-water interface and ensure significant lowering of the nanobubble contact angle and Laplace pressure even at relatively small impurity coverage. In fact for impurity molecules that show enhanced tendency to get adsorbed at the nanobubble air-water interface from the bulk phase, impurity-induced lowering of the nanobubble contact angle is witnessed for extremely small bulk concentration. Surface nanobubble experiments being typically performed in an ultraclean environment, the bulk concentration of impurities is inevitably very small, and in this light the present calculations can be viewed as a satisfactory explanation of the conjecture that impurities, even in trace concentration, have significant impact on surface nanobubble

Enteropathogen survival in soil from different land-uses is predominantly regulated by microbial community composition

peer-reviewedMicrobial enteropathogens can enter the environment via landspreading of animal slurries and manures. Biotic interactions with the soil microbial community can contribute to their subsequent decay. This study aimed to determine the relative impact of biotic, specifically microbial community structure, and physico-chemical properties associated with soils derived from 12 contrasting land-uses on enteropathogen survival. Phenotypic profiles of microbial communities (via phospholipid fatty acid (PLFA) profiling), and total biomass (by fumigation-extraction), in the soils were determined, as well as a range of physicochemical properties. The persistence of Salmonella Dublin, Listeria monocytogenes, and Escherichia coli was measured over 110 days within soil microcosms. Physicochemical and biotic data were used in stepwise regression analysis to determine the predominant factor related to pathogen-specific death rates. Phenotypic structure, associated with a diverse range of constituent PLFAs, was identified as the most significant factor in pathogen decay for S. Dublin, L. monocytogenes, non-toxigenic E. coli O157 but not for environmentally-persistent E. coli. This demonstrates the importance of entire community-scale interactions in pathogen suppression, and that such interactions are context-specific

PEMBUATAN DENAH PANDUAN KAMPUS D UNIVERSITAS GUNADARMA PADA TELEPON GENGGAM MENGGUNAKAN J2ME

Dilain pihak kemajuan teknologi telepon genggam sudah dapat memungkinkan pencarian informasi melalui telepon genggam. Sehingga informasi yang tepat, cepat dan dapat diakses kapan saja menjadi terpenuhi. Berdasarkan hal tersebut pada penelitian ini dibuat program aplikasi untuk menampilkan denah lokasi pada telepon genggam yang dikhususkan untuk kampus D Universitas Gunadarma. Tujuan dari penelitian ini adalah mempermudah dalam rangka pencarian lokasi ruangan di kampus D Universitas Gunadarma melalui telepon genggam, selain itu juga dapat mengukur jarak denah, memberikan informasi keterangan ruangan dan menampilkan detail ruangan. Agar aplikasi ini dapat berjalan dibanyak telepon genggam yang mendukung Java, pada proses pembuatannya menggunakan bahasa pemrograman J2ME (Java 2 Micro Edition). Berdasarkan pada hasil uji coba, menunjukkan bahwa aplikasi pencarian lokasi ruangan kampus D Universitas Gunadarma berhasil diimplementasikan dengan dukungan bahasa pemrograman Java

Use of the Micro-Deval Test for Assessing Alaska Aggregates

INE/AUTC 12.1